I was wondering if you guys have more information about the STA system in ToS, as far I have been told it's tied into the travelling and replenished via large blue crystals wrapped tightly in the Earth's green mandible out in the fields.

Stamina is used for certain skills, e.g. movement for Sorcerer's summon. Some classes also have dashing skills, which may or may not consume stamina. Other than those, it's a classic and straightforward feature.